Warp clamp

ABSTRACT

A warp clamp draws the warp sheet between relatively fixed jaws of the clamp by a rolling action and usually requires the services of only one man to perform the clamping operation.

United States Patent Townsend 1 Oct. 10, 1972 WARP CLAMP [56] References Cited [72] Inventor: Franklin L. Townsend, Rockford UNITED STATES PATENTS wmnebag" 2,993,2s9 7/1961 Friend et a]; ..28/32 I Assignee; Barber-Colman 1 Meierhofer 3,380,133 4/1968 Meierhofer ..28/44 Rockford, Ill. 3,534,921 10/1970 Koslowski ..28/32 X [22] Filed: May 10, 1971 Primary Examiner-Louis K. Rimrodt [21] PP 141,549 Attorney-A. Richard Koch 52 US. Cl ..2s/44, 28/725 [57] ABSTRACT [51] Int. Cl. ..D03j 1/16 A a p a p draws he warp sheet between relatively 58 Field of Search ..2s/22, 32, 35, 32.5, 44, 72.5 fixed jaws of the clamp by a rolling action and usually requires the services of only one man to perform the clamping operation.

12 Claims, 5 Drawing Figures P'A'TENTEDum 10 m2 INVENTOR Fray/Kim L. Townsend AG ENT l WARP CLAMP BACKGROUND OF THE INVENTION This invention is concerned with warp clamps employed on warp drawing machines, warp tying machines, and the like.

In preparation for weaving cloth on a loom, thread destined to become the warp is wound on a warp beam, which is moved into a warp drawing machine, where the warp ends are separated fromthe beam and loosely engaged by a plush clamp to form a warp sheet. A

drawing-in needle draws a leading thread of the sheet from the plush clamp and through a predetermined selection of drop wire, heddle, and reed dent. The process is repeated until all warp ends have been drawn in It is essential that the warp be taut and that the collective tension on the warp threads not rotate the beam. In order to prevent such rotation, a warp clamp has been employed to grip and hold the warp sheet between the beam and the needle. In the past warp clamps long enough to be used with wide warp sheets were not sufficiently rigid to grip the entire width of the sheet without employing additional manpower to properly seat the insertion bar between the jaws of the clamp.

When one warp sheet is exhausted, warp ends from a new warp sheet are tied to respective tail ends of the exhausted sheet by a warp tying machine. Warp clamps are employed to hold the sheet during the tying operation.

SUMMARY OF THE INVENTION This invention covers a method for clamping a warp sheet while the warp is being drawn into a loom harness or tied to an exhausted warp sheet. It also covers a yarn clamp utilizing this method. The yarn is automatically tensioned in one direction, and cannot be pulled out of the clamp. The clamp tightens its grip on the yarn when a pull is exerted by the yarn. The clamp is easily loaded, light in weight and inexpensive to manufacture.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a front elevation of the warp clamp with the warp sheet in clamped position.

FIG. 2 is a partially sectioned end view from the left of FIG. 1 illustrating a method of loading.

FIG. 3 is a section taken along the line 3-3 of FIG. 2 showing a construction detail. I

FIG. 4 is a section taken along the line 4-4 of FIG. 1 showing the clamping position of the various parts.

FIG. 5 is a vector diagram of the clamping forces.

DESCRIPTION OF THE PREFERRED EMBODIMENT When warp from a new warp beam is to be drawn into a loom or tied to ends of warp already in the loom it is brought to a warp drawing or tying machine on a warp beam, from which the warp ends are separated and loosely engaged by a plush clamp to form a warp sheet 11.

FIG. 1 shows a warp sheet 11 extending vertically from a warp beam (not shown) at the bottom to a plush clamp (not shown) at the top and gripped by and securely held in a warp clamp 12. The warp clamp is fastened to the frame 13 of a warp drawing machine,

warp tying machine, or the like. The warp sheet 11 comprises a plurality of threads 15 arranged side by side in a single layer between the warp beam and the plush clamp. All of the threads 15 comprising the warp sheet 11, regardless of width, are to be held securely in the warp clamp 12.

As best seen in FIG. 2 an extruded channel 16, having a pair of opposed flanges 17, 18 joined by a web 19, forms the backbone of the warp clamp 12. A strip of an elastomer such as extruded natural or synthetic rubber forms a resilient jaw 20 affixed to the inside of the flange 17 and extending continuously therealong for at least the width of the warp sheet 11 and-preferably for the entire length of the flange. An intumed rim 21 on flange 17 assistsin retaining the jaw 20 in the channel 16. A crankshaft 22 extending lengthwise through the channel 16 serves as a revolving rigid jaw. It is shown as a smooth roundshaft joumaled in a rigid open bearing 23 retained in the channel 16 against the flange 18 between the web 19 and an intumed rim 24, and in parallel spaced relation to the resilient jaw 20. The bearing 23 may be an extrusion of nylon extending the entire length of the channel and having a concave surface closely fitting more than half way around the crankshaft 22 to support and restrain the crankshaft in fixed relation to the channel 16 and the resilient jaw 20. As best seen in FIG. 3, end plates 26, affixed to the ends of channel 16 as by screws 27, may assist in preventing endwise movement of the extrusions 20 and 23, and cooperate with collars 28, affixed to the crankshaft 22 as by set screws 29, to prevent axial movement of the crankshaft. A crankhandle 30, as shown in FIG. 1, may be keyed to an overhanging end 31 of the crankshaft 22 to rotate the latter. The above described assembly is mounted on the frame 13 behind the warp sheet 11, as seen in FIGS. 1 and 2. It will be seen that when the warp sheet 11 is formed by separating the ends of threads 15 from the warp beam below the warp clamp 12 and loosely engaging them to the plush clamp above the warp clamp they are passed before the jaws 20 and 22 of the warp clamp 12 as shown in FIGS. 1 and 2.

An insertion bar 33, shown as cylindrical and sized to have an interference fit between the resilient jaw 20 and the rigid jaw or crankshaft 22, is positioned to extend across and before the warp sheet 11, parallel to the jaws, and opposite the space between them. The bar 33 is moved into engagement with both jaws 20, 22 by means shown as a toggle clamp 34. A pair of such clamps are shown in FIG. 1-1 on either side of the warp sheet 11. The toggle clamp 34 is mounted in fixed relation to the channel 16 as by a bracket 35 and spaced-before the plane of the warp sheet 11. The inoperative position of toggle clamp 34 is shown in solid lines in FIG. 2. A handle 36 and a lever 37 are movable about spaced axes 38 and 39 respectively on a base 40, and a toggle link 41 interconnects the handle and lever between pivots 42, 43. An adjusting screw 44 on the free end of lever 37 provides means for adjusting the point at which force is delivered by the toggle clamp 34. As the handle 36 is raised to the dashed line position 36, the lever 37 is turned about the axis 39 by action of link 41 to the vertical dashed line position 37'. The base 40 is fastened to bracket 35 in such a location that the screw 44 is aligned with the insertion bar 33 when in the operated dashed line position 44'. The screw transmits the force required to move the insertion bar 33 into the dashed line position 33' in the space between the jaws 20 and 22. As the bar is moved into the space, it carries with it a portion 11' shown in dashed lines of the warp sheet 11 which is pinched between the insertion bar and both the resilient jaw 20 and the rigid jaw or crankshaft 22.

After the insertion bar has been moved to position 33, the crankshaft 22 is rotated as by crankhandle 30 in counterclockwise direction as shown in FIG. 2, rolling the insertion bar in a clockwise direction and to the left across the resilient jaw 20. The rolling of the bar 33 across the jaw 20 compresses the jaw so that it exerts a generally downward force, represented by the vector F l in FIG. 5. Another force represented by the vector F2 is variable in direction in agreement with a line 46 joining the centers of the bar 33 and crankshaft 22. The upward component of the force represented by vector F2 is balanced by the downward force represented by vector F1, leaving a resultant force represented by the vector R directed to the right as shown in solid lines before insertion bar 33 is rolled over the center of crankshaft 22 and to the left as shown by the dashed vector R after the bar has been rolled overcenter as shown in FIG. 4 and by the dashed vector F2. Once the insertion bar 33 has been rolled overcenter, the force represented by the resultant vector R will provide a bias tending to move the bar farther overcenter. This rolling action and overcenter motion is utilized to securely hold each of the threads 15 comprising the yarn sheet 11.

As seen in FIG. 4 the insertion bar 33 is made of rigid core 47 supporting a resilient surface 48 employed to better grip the individual threads 15. This surface could be in the form of an extruded tube of elastomeric material such as polyurethane slipped over a metal core. As a result of the resilience of both the jaw and surface 48, all of the threads 15 are engaged over a large portion of their circumference between said resilient jaw and surface. As the bar 33 rolls over resilient jaw 20, there is no relative motion between the pinched threads 15 and the jaw, and there is no additional tension created in the upper portion 11a of the warp sheet 1 1. At the same time the lower portion 11b is being pulled further into the space between the jaws 20 and 22 by the rolling action of insertion bar 33 driven by the revolving jaw or crankshaft 22 with the threads 15 pinched between. This pulling creates additional equal tension in each thread 15 in portion 11b of the warp sheet and may result in some rotation of the warp beam to supply the additional length of thread required by the pulling in. After bar 33 has rolled overcenter, the downward force exerted by resilient jaw 20 on the bar 33 tends to continue clockwise rotation of the bar and pulling on the portion 11b until movement of the bar to the left is stopped by the web 19, or as a result of the resultant force being eliminated when the bar rolls off of the crankshaft 22. Any motion after the bar has moved overcenter is automatic and independent of external means for rotating the crankshaft. It will be noted that the downward force exerted by the resilient jaw 20 is at its maximum as the insertion bar 33 rolls overcenter because the jaw is compressed most at that time and that the downward force decreases as the bar moves away from the overcenter position. If then, after the bar has moved overcenter, a tension is exerted on the threads 15 in portion 11a, this tension will be strongly opposed-firstly because there should not be any relative movement between the thread 15 and the stationary resilient jaw 20, secondly because the high coefficient of friction between the thread and both the jaw and the bar 33, both of which are resilient, greatly reduces any possibility of slippage, and thirdly because any pull executed by the thread would tend to roll the bar 33 up the surface of crankshaft 22, increasing compression of the resilient jaw 20 and so increasing the frictional force opposing slippage.

The insertion bar 33, being long to extend across the warp sheet 11 and of small diameter to keep the size of the warp clamp as small as possible while serving its function, is flexible and will not by itself pinch all of the threads 15 in the warp sheet against both jaws 20 and 22 when the bar is moved forward by the toggle clamps 34. To overcome this difficulty, a back-up member is employed to stiffen the insertion bar. As shown in FIG. 2 this back-up member takes the form of a rigid tube or roll 49 of considerably larger diameter than the insertion bar. This back-up member is interposed between the insertion bar 33 and the adjusting screws 44 on toggle clamps 34 and is supported as on portions 50 of the brackets 35 mounting the toggle clamps 34. Due to the large diameter of the tube 49, it is relatively inflexible and will exert substantially uniform force against the entire length of the insertion bar 33 when the toggle clamps 34 have been moved to operated position 34. The bar will therefore pinch each thread 15 substantially equally against the jaws 20 and 22 and be in optimum position to be rolled into the space between the jaws and eventually overcenter.

When the warp sheet 11 is to be released, the crankshaft 22 is rotated in clockwise direction, rolling the insertion bar 33 counterclockwise and to the right over the resilient jaw 20. In doing so, the bar will be moved overcenter and out of the space between the jaws 20, 22 to release the sheet.

The core 47 and the tube 49 are preferably extrusions of a light metal such as aluminum so that they may be more easily handled and so that there is less tendency to flex as a result of their own weight. The channel 16 may also be of light metal although lightness is not so much of a factor. Extrusions are inexpensive and since most of the components are made of extrusions, or readily obtainable simple parts, the entire warp clamp is low in cost.

It is to be understood that the drawings and the above description cover only a preferred embodiment of the invention, and that they are merely representative of the invention, the scope of which is limited only by the claims.

I claim:

1. A method for clamping a warp sheet during drawing in, tying, and the like comprising the steps of passing the warp sheet before a fixedly supported elongated resilient jaw and an elongated rigid jaw journaled in parallel fixed spaced relation to said resilient jaw, positioning an insertion bar on the opposite side of the warp sheet and parallel to said jaws, moving the insertion bar to pinch said sheet against both of the jaws, and rotating the rigid jaw in a direction to pull the sheet between the insertion bar and said rigid jaw and to roll the insertion bar across the resilient jaw.

2. A method according to claim 1 whereby the insertion bar is rolled overcenter with respect to said rigid aw.

3. A clamp for gripping and holding threads of a warp sheet comprising a crankshaft, an elongated resilient jaw, means for rigidly supporting said jaw in parallel fixed spaced relation to said crankshaft, an insertion bar having an interference fit between said spaced resilient jaw and said crankshaft, means for moving the bar against both the jaw and the crankshaft, and means for rotating the crankshaft to roll the bar across the resilient jaw whereby the threads of said warp sheet are pinched between the bar and both of said crankshaft and said jaw and then pulled between the crankshaft and said bar.

4. A clamp according to claim 3 wherein said crankshaft is positioned to roll the bar overcenter whereby the bar is automatically biased to securely hold said thread.

5. A clamp according to claim 3 wherein said resilient jaw is made of an elastomer.

6. A clamp according to claim 3 wherein said insertion bar comprises a rigid core supporting an elastomeric surface.

7. A clamp according to claim 3 wherein said means for moving the insertion bar is a toggle clamp and additionally comprising means for mounting said toggle clamp in fixed relation to the means for supporting said jaw, a portion of said toggle clamp applying a force for moving the bar toward both said jaw and said crankshaft.

8. A clamp according to claim 3 additionally comprising a substantially inflexible back-up member introduced between said insertion bar and the means for moving said bar.

9. A clamp according to claim 8 wherein said backup member is a cylindrical tube.

10. A clamp according to claim 3 wherein the means for supporting said jaw is an elongated rigid channel having first and second opposed flanges connected by a web, said resilient jaw supported by and extending along the inside of the first flange, and said crankshaft journaled within the channel.

11. A clamp according to claim 10 wherein said crankshaft is journaled substantially throughout the length of said channel in an open rigid bearing.

12. A clamp according to claim 11 wherein said bearing is a plastic extrusion. 

1. A method for clamping a warp sheet during drawing in, tying, and the like comprising the steps of passing the warp sheet before a fixedly supported elongated resilient jaw and an elongated rigid jaw journaled in parallel fixed spaced relation to said resilient jaw, positioning an insertion bar on the opposite side of the warp sheet and parallel to said jaws, moving the insertion bar to pinch said sheet against both of the jaws, and rotating the rigid jaw in a direction to pull the sheet between the insertion bar and said rigid jaw and to roll the insertion bar across the resilient jaw.
 2. A method according to claim 1 whereby the insertion bar is rolled overcenter with respect to said rigid jaw.
 3. A clamp for gripping and holding threads of a warp sheet comprising a crankshaft, an elongated resilient jaw, means for rigidly supporting said jaw in parallel fixed spaced relation to said crankshaft, an insertion bar having an interference fit between said spaced resilient jaw and said crankshaft, means for moving the bar against both the jaw and the crankshaft, and means for rotating the crankshaft to roll the bar across the resilient jaw whereby the threads of said warp sheet are pinched between the bar and both of said crankshaft and said jaw and then pulled between the crankshaft and said bar.
 4. A clamp according to claim 3 wherein said crankshaft is positioned to roll the bar overcenter whereby the bar is automatically biased to securely hold said thread.
 5. A clamp according to claim 3 wherein said resilient jaw is made of an elastomer.
 6. A clamp according to claim 3 wherein said insertion bar comprises a rigid core supporting an elastomeric surface.
 7. A clamp according to claim 3 wherein said means for moving the insertion bar is a toggle clamp and additionally comprising means for mounting said toggle clamp in fixed relation to the means for supporting said jaw, a portion of said toggle clamp applying a force for moving the bar toward both said jaw and said crankshaft.
 8. A clamp according to claim 3 additionally comprising a substantially inflexible back-up member introduced between said insertion bar and the means for moving said bar.
 9. A clamp according to claim 8 wherein said back-up member is a cylindrical tube.
 10. A clamp according to claim 3 wherein the means for supporting said jaw is an elongated rigid channel having first and second opposed flanges connected by a web, said resilient jaw supported by and extending along the inside of the first flange, and said crankshaft journaled Within the channel.
 11. A clamp according to claim 10 wherein said crankshaft is journaled substantially throughout the length of said channel in an open rigid bearing.
 12. A clamp according to claim 11 wherein said bearing is a plastic extrusion. 